[R] Get means of matrix

[Jesús Para Fernández]

Hi everyone

I have a dataframe "data" wich is the result of join multiple csv (400 rows and 600cols every csv). The "data" dataframe has n rows and m columns (200000 rows and 600 cols) , and I have add a new colum, "csvdata", in which I specify the number of csv at wich those data belong. 

So, the dataframe "data" looks like:

x1    x2     x3    ....    xn    csvdata
21   23    32    ....    12    1
27   21    39    ....    14    1
24   22    30    ....    11    1
..............................................
21   24    32    ....   19     2
27   21    39    ....    14    2
..............................................
27   22     30    ....    11    n

   

I want to store into a matrix the mean values of different substes of data of every csv, for example: 

region1,1 (rows 1:20,columns 1:20) for every "csvdata" value
region 2,1 (rows 21:40,columns 1:20) para every "csvdata" value
....

And so on for hole data.frame. 

I have tryed:

area1<-tapply(as.matrix(data[1:20,1]),datos$csvdata,mean,na.rm=T)
area2<-tapply(as.matrix(data[1:20,1]),datos$csvdata,mean,na.rm=T)

But this error is the output I obtain:
 
Error in tapply(data[1:30, ], datos$nueva, mean, na.rm = T) : 
  arguments must have same length

I´m sure that it is not very complex to do it, but I have no idea of how to do it.

Thanks for all. 

 		 	   		   		 	   		  
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